The invention relates to an active substance-containing patch for controlled release of estradiol or its pharmaceutically acceptable derivatives, alone or in combination with gestagens, to the human or animal skin.
Estrogen-and/or gestagen-containing patches are already known. They do, however, have disadvantages in that they either contain ethanol or involve the potential danger of the active substance recrystallizing in the course of time.
From DE-OS 32 05 258 and EP 0 285 563 it is known to simultaneously administer estradiol and ethanol in a patch formulation. The production of this patch is, however, very complicated, and the patches have little wearing comfort after they have been applied, since they lack flexibility.
EP 0 285 563 describes a transdermal therapeutic system for the combined application of estrogens and gestagens. The reservoir contains the active substance formulation and optionally a membrane, as well as ethanol as percutaneous, absorption-enhancing agent. Since the release of active substance is mainly controlled by the membrane, this transdermal therapeutic system is fundamentally different from the active substance patch according to the present invention. In the patch described by this document, the adhesive merely has the function of fixing the patch on the skin. The fact that it is capable of contributing to the control of the active substance release does not constitute its main task, but is merely axe2x80x94possibly even unwantedxe2x80x94side effect. The patch is a so-called xe2x80x9cpouch patchxe2x80x9d, since the active substance formulation is present within a pouch, consisting of an impermeable backing layer and a membrane with adhesive layer. As a consequence of its complicated structure, the production of this patch requires great expenditure since the individual components must be prepared separately and then, in a further process step, combined to form a patch.
EP 0 275 716 describes a transdermal two-layer systemxe2x80x94in contrast to the mono-layer system of the present inventionxe2x80x94for simultaneous administration of one or more estrogens, which are dissolved or microdispersed in the polymer layer. Here, the pressure-sensitive layer contains, apart from the active compounds, substances which enhance transdermal absorption. Polymer and pressure-sensitive layers may consist of polyacrylates, silicones or polyisobutylenes.
EP 0 328 806 describes a membrane-free transdermal therapeutic system the matrix of which consists of a polyacrylate adhesive, a solvent, a penetration enhancer and estrogens, its derivatives and combinations thereof.
WO 87/07138 describes an estradiol patch comprising a backing layer, a matrix containing the active substance, and a pressure-sensitive adhesive, which adhesive is covered by a removable protective layer. The production of the matrix and pressure-sensitive adhesive is carried out in process steps requiring a great expenditure in terms of the technology to be applied, by homogenizing, degasifying, coating, drying and separating into individual pieces. In one embodiment, the backing layer must even be coated with a pressure-sensitive adhesive, which means a further process step. The combining of the individual parts takes place in a separate process step. The overall production of the patch thus involves great expenditure and is complicated.
From U.S. Pat. No. 4,624,665, systems are known which contain the active substance in microencapsuled form in the reservoir. The reservoir is embedded between a backing layer and a membrane. The outer margin of the system is provided with a pressure-sensitive adhesive. The structure and production of this system is very complicated since the active substance must be microencapsulated and distributed in a homogenous phase, which then, in further process steps, must be embedded between backing layer and membrane. In addition, the system must then be provided with an adhesive margin and covered with a protective layer.
Further, from EP 0 186 019 active substance patches are known wherein to a rubber/adhesive resin mass are added water-swellable polymers, and from which patches estradiol can be released. It has, however, emerged that the release of estradiol from these active substance patches is too low by far and does not meet therapeutic requirements.
In DE-OS 20 06 696 a patch or an adhesive bandage is described which has systematic action and wherein contraceptive substances are incorporated in the adhesive component or the adhesive film. The adhesive film may be an acrylate.
It is thus the object of the present invention to avoid the above-mentioned disadvantages and to provide a stable, i.e. recrystallization-free, estrogen-and/or gestagen-containing patch having sufficient active substance release, whose release is not subject to change by storage.
Surprisingly, it has emerged that this object is achieved by an estrogen-and/or gestagen-containing pressure-sensitive adhesive which contains wool wax, also known as lanolin wax, or constituents thereof and zinc oxide.
The above-described object is thus achieved by an active substance-containing patch according to the main claim. The subclaims relate to especially preferred embodiments of the subject matter of the invention.
Wool wax is known as a pharmaceutical raw material and is described as such by the pharmacopoeias. It is used because of its liberating capacity for active substances, its being well tolerated by the skin and its absorption capacity for water.
Zinc oxide is also described in the pharmacopoeias. Zinc oxide acts as a mild disinfectant and is antiphlogistic, furthermore it reacts faintly alkaline.
The active substance patch according to the invention can be used for cosmetic as well as therapeutic purposes in human and veterinary medicine.
The recrystallization-free estrogen-and/or gestagen-containing patch having sufficient active substance release contains in its reservoir estradiol and its pharmaceutically acceptable derivatives, alone or in combination with gestagens, in a concentration of a total of 1-20%-wt., relative to the totality of the reservoir components, in fact in a molar ratio of 1:1 to 1:10.
The estradiol-containing reservoir may contain at least one component belonging to the group comprising age-protecting agents, plasticizers, antioxidants and absorption enhancers. Suitable plasticizers are known to those skilled in the art, and are described, for example, in DE 37 43 946. The estradiol-containing reservoir usually contains plasticizers in a portion of up to 5%-wt.
Furthermore, the reservoir contains age-protecting agents in a concentration of up to 1%-wt. These are known to those skilled in the art and are described, for example, in DE 37 43 946.
The materials for the impermeable backing layer and the detachable protective layer are also known to those skilled in the art.
The estradiol-containing reservoir may be made from the solution, dispersion and from the melt.
In case the reservoir has no sufficient inherent tack on the skin, it can be provided with an additional active substance-free pressure-sensitive adhesive or with a circumferential pressure-sensitive adhesive margin. In this way it is ensured that the transdermal patch adheres on the skin over the entire period of application.
A particularly preferred structure of the transdermal estradiol-containing patch is a matrix system, wherein, as is known, the matrix takes over the control of the active substance release and is subject to the t-law according to Higuchi. This does not mean, however, that a membrane system is not of advantage in special cases. In membrane systems, an active substance release-controlling membrane is located between reservoir and pressure-sensitive adhesive layer.
The thickness of the transdermal patch is dependent on the therapeutic requirements and can be adjusted accordingly. Usually, it ranges from 0.03-0.6 mm.